'Shamrock Shake' on Serious Eats

People go gaga over this drink: each Shamrock season, blogs (like, well, us) and news sites around the country hail its return to the McDonald's menu, and there's even an entire website, shamrockshake.com, devoted to tracking down the milkshake (which, presumably, will be a lot easier to do this year, but that hasn't stopped users from breathlessly posting local "sightings"). What is it about this soft-serve creation that gets people so fired up? More